Image forming apparatus and image forming method thereof

ABSTRACT

An image forming apparatus is provided. The image forming apparatus includes a communication interface unit which receives print data, a rendering unit which converts the received print data into a bitmap image by rendering, a binarization unit which generates binary data by carrying out halftoning with respect to the bitmap image, a data combining unit which generates multi-bit data by combining a plurality of successive binary data of the generated binary data, and a print engine which forms an image on a print paper using the generated multi-bit data.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. Ser. No.13/031,819 filed in the United States on Feb. 22, 2011, and is relatedto, and claims priority benefit of Korean Patent Application No.10-2010-0089874, filed on Sep. 14, 2010, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference.

BACKGROUND

1. Field

Apparatuses and methods consistent with the disclosure provided hereinrelate to an image forming apparatus and an image forming methodthereof, and more particularly to an image forming apparatus and animage forming method thereof which provide outputs at 1200×1200 dpiresolution by forming part of combined data as half-size dots.

2. Description of the Related Art

An image forming apparatus operates to print out print data generated ata terminal, such as a computer, onto a print medium. The examples of theimage forming apparatus may include a copier, a printer, a facsimile, ora multi function peripheral (MFP) which integrates therein theabove-mentioned functions.

Conventionally, when received print data has higher resolution than theresolution supported by the image forming apparatus, the image formingapparatus converts print data to a lower resolution before carrying outprint job.

For example, if print data at 1200×1200 dpi resolution is received atthe image forming apparatus which supports 1200×600 dpi resolution,conventionally, the image forming apparatus carries out rendering andbinarization with respect to the received data at 1200 dpi, converts thebinarized data into data at 600 dpi at final step and carries out theprint job. This means that the conventional image apparatus outputsresolution of 600×600 dpi.

Accordingly, the conventional image forming apparatus cannot supportprint jobs that require resolution higher than 600 dpi, such as printjob related to CAD, blueprint, or fingerprint. Accordingly, an imageforming method is necessary, which is capable of providing output atresolution as high as 1200 dpi in any circumstances.

SUMMARY

Exemplary embodiments overcome the above disadvantages and otherdisadvantages not described above. Also, the embodiments are notrequired to overcome the disadvantages described above, and an exemplaryembodiment may not overcome any of the problems described above.

According to one embodiment, an image forming apparatus and an imageforming method are provided, which provide output at 1200×1200 dpiresolution by combining binary data and forming part of the compositeddata as half-size dots.

According to an exemplary embodiment, an image forming apparatus mayinclude a communication interface unit which receives print data, arendering unit which converts the received print data into a bitmapimage by rendering, a binarization unit which generates binary data bycarrying out halftoning with respect to the bitmap image, a datacombining unit which generates multi-bit data by combining a pluralityof successive binary data of the generated binary data, and a printengine which forms an image on a print paper using the generatedmulti-bit data.

The received print data may be raw data with 1200×1200 dpi (dots perinch) resolution.

The rendering unit may generate bitmap data at 1200×1200 dpi resolutionfrom the received print data.

The print engine unit may have 1200 dpi resolution in a main-scandirection and 600 dpi resolution in a sub-scan direction.

The data combining unit may combine a plurality of successive binarydata in an advancing direction of the print paper.

The data combining unit may generate at least one 2-bit data from among‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’, by combining two binary datain a vertical direction from among the binary data.

The print engine unit may form at least one of: white dot, half-sizedot, and full-size dot.

The print engine unit may form the half-size dot with respect to ‘01₍₂₎’ and ‘10 ₍₂₎’ of the 2-bit data.

The dot formed by the half-size dot may have 1200 dpi pitch.

In another exemplary embodiment, an image forming method of an imageforming apparatus is provided, in which the image forming method mayinclude receiving print data, rendering to convert the received printdata into a bitmap image, halftoning with respect to the bitmap image togenerate binary data, data combining to generate multi-bit data bycombining a plurality of successive binary data of the generated binarydata, and forming an image on a print paper using the generatedmulti-bit data.

The received print data may be raw data with 1200×1200 dpi (dots perinch) resolution.

The rendering may include generating bitmap data at 1200×1200 dpiresolution from the received print data.

The forming an image may include using a print engine having 1200 dpiresolution in a main-scan direction and 600 dpi resolution in a sub-scandirection.

The data combining may include combining a plurality of successivebinary data in an advancing direction of the print paper.

The data combining may include generating at least one 2-bit data fromamong ‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’, by combining two binarydata in a vertical direction from among the binary data.

The forming an image may include forming at least one of: white dot,half-size dot, and full-size dot.

The forming an image may include forming the half-size dot with respectto ‘01 ₍₂₎’ and ‘10 ₍₂₎’ of the 2-bit data.

The dot formed by the half-size dot may have 1200 dpi pitch.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingcertain exemplary embodiments with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram of an image forming apparatus according to anexemplary embodiment;

FIGS. 2 and 3 are views provided to explain changes in print dataaccording to an exemplary embodiment;

FIG. 4 is a view illustrating property of a laser signal in a main-scandirection;

FIGS. 5 to 8 are views illustrating property of a laser signal in asub-scan direction; and

FIG. 9 is a flowchart provided to explain an image forming methodaccording to an exemplary embodiment.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described in greater detailwith reference to the accompanying drawings.

In the following description, same drawing reference numerals are usedfor the same elements even in different drawings. The matters defined inthe description, such as detailed construction and elements, areprovided to assist in a comprehensive understanding embodiments.Accordingly, it is apparent that the exemplary embodiments can becarried out without those specifically defined matters. Also, well-knownfunctions or constructions are not described in detail since they wouldobscure the description with unnecessary detail.

FIG. 1 is a block diagram of an image forming apparatus according to anexemplary embodiment.

Referring to FIG. 1, an image forming apparatus 100 includes acommunication interface unit 110, a storage unit 120, a user interfaceunit 130, a rendering unit 140, a binarization unit 150, a datacombining unit 160, a print engine unit 170, and a control unit 180.

The communication interface unit 110 is provided to connect the imageforming apparatus 100 to a print control terminal 10, via not only localarea network (LAN) and Internet, but also universal serial bus (USB)port. The communication interface unit 110 may receive print data fromthe print control terminal 10. The received print data may have1200×1200 dpi resolution, or the data may be in a form of vector data.

The communication interface unit 110 may receive a resolution optionfrom the print control terminal 10. To be specific, a user may set aprint resolution with a print driver which is installed on the printcontrol terminal 10. Accordingly, if the user sets 1200 dpi resolutionoutput with the print driver, the print control terminal 10 may transferto the image forming apparatus 100 “1200 dpi resolution option”, thusindicating that the output has to be carried out at 1200 dpi resolution.

In actual implementation, the image forming apparatus 100 may be set tocarry out 1200 dpi resolution print job only upon receipt of “1200 dpiresolution option” from the print control terminal 10. However, theimage forming apparatus 100 may also carry out 1200 dpi resolution printjob without receiving “1200 dpi resolution option”, if the receivedprint data has a 1200×1200 dpi resolution.

The storage unit 120 stores therein print data. To be specific, thestorage unit 120 stores therein the print data received via thecommunication interface unit 110. The storage unit 120 may additionallystore therein data processed at the rendering unit 140, the binarizationunit 150 and the data combining unit 160 (e.g., bitmap data, binarydata, multi-bit data, or the like). Meanwhile, the storage unit 120 maybe implemented as an internal storage medium of the image formingapparatus, or an external storage medium, such as a removable diskincluding USB memory, or Web server via network. In one embodiment, onlyone storage unit 120 is illustrated and explained. However, this iswritten only for illustrate purpose, and accordingly, the storage unit120 may be divided into a memory for data storage, memory for commandprocessing, or the like.

The user interface unit 130 includes a plurality of function keys withwhich a user sets or selects a variety of functions supported by theimage forming apparatus, and may display various information provided bythe image forming apparatus 100. The user interface unit 130 may beimplemented as a combination of a monitor and a mouse, or as a devicesuch as touchpad which is capable of both inputting and outputting.

The rendering unit 140 converts received print data into bitmap image byrendering. To be specific, the rendering unit 140 may generate a bitmapimage by carrying out rendering with respect to the print data receivedfrom the print control terminal 10. Herein, the rendering unit 140 mayconvert raw data at a resolution of 1200×1200 dpi into bitmap image witha 1200×1200 dpi resolution, and also convert raw data or vector data atresolution lower than 1200×1200 dpi into bitmap image at a 1200×1200 dpiresolution. The generated bitmap image may be stored at the storage unit120 temporarily.

The binarization unit 150 generates binary data by carrying outhalftoning with respect to the bitmap image. To be specific, thebinarization unit 150 carries out halftoning including, for example,screening or dithering with respect to the bitmap image rendered at therendering unit 140, to thus generate binary data (1200×1200×1 bit). Thegenerated binary data may be stored temporarily at the storage unit 120.To be specific, the storage unit 120 may store the generated binary databy writing the generated binary data over the previously stored bitmapimage, or alternatively, store the generated binary data at a separatelocation.

The data combining unit 160 combines successive binary data of thegenerated binary data to generate multi-bit data. To be specific, thedata combining unit 160 may generate at least one 2-bit data from among‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’ by combining two successivebinary data in the advancing direction (i.e., sub-scan direction) of theprint paper. By way of example, if data ‘0 ₍₂₎’, ‘0 ₍₂₎’, ‘0 ₍₂₎’, ‘1₍₂₎’ successively exist in the sub-scan direction, the data combiningunit 160 may generate two 2-bit data of ‘00 ₍₂₎’, ‘01 ₍₂₎’. Theoperation of the data combining unit 160 will be explained in greaterdetail below with reference to FIG. 3.

The storage unit 120 may store the multi-bit data generated at the datacombining unit 160. To be specific, the storage unit 120 may store thegenerated multi-bit data, by writing the generated multi-bit data overthe address of the previously-stored binary data.

The print engine unit 170 forms an image using the generated multi-bitdata. To be specific, the print engine unit 170 may use a print enginewith the resolution of 1200 dpi in main-scan direction and 600 dpi insub-scan direction.

The print engine unit 170 generates a plurality of dots to correspond tothe multi-bit data transferred from the data combining unit 160, andattach toner to the generated dots to thus form an image. Herein, theprint engine unit 170 may generate dots, such as white dots, half-sizedots, or full-size dots.

To be specific, the print engine unit 170 may form a white dot if themulti-bit data transferred from the data combining unit 160 is ‘00 ₍₂₎’,forms a half-size dot if the transferred multi-bit data is ‘01 ₍₂₎’ and‘10 ₍₂₎’, and forms a full-size dot if the transferred multi-bit data is‘11 ₍₂₎’. The half-size dot may have 1200 dpi pitch.

As explained above, the print engine unit 170 according to an exemplaryembodiment receives and processes data at 600 dpi level, but appliesresolution enhancement technology (RET) to form three different forms ofdots depending on the multi-bit information. As a result, the printengine unit 170 is capable of outputting at the output resolution of1200 dpi. The RET operation of the print engine unit 170 will beexplained in greater detail below with reference to FIGS. 3 to 8.

The control unit 180 controls the respective components of the imageforming apparatus 100. To be specific, the control unit 180 may controlthe storage unit 120 to temporarily store print data, if the print datais received from the print control terminal 10.

The control unit 180 may also control the rendering unit 140, thebinarization unit 150, the data combining unit 160 and the print engineunit 170 to print out the print data stored at the storage unit 120 atthe resolution of 1200 dpi.

As explained above, the image forming apparatus 100 according to anexemplary embodiment converts only the form of the binary data at1200×1200 dpi resolution without affecting the data itself, andtransfers the converted data to the print engine. Then as the printengine forms half-size dots at 1200 dpi pitch with respect to ‘01 ₍₂₎’and ‘10 ₍₂₎’ of the transferred multi-bit data, the print job is carriedout at the resolution of 1200×1200 dpi as desired by the user.

FIGS. 2 and 3 are views provided to explain changes in the print dataaccording to an exemplary embodiment.

First, at operation 210, the user may select or write a file that heintends to print out using the print control terminal 10. At operation220, if the 1200 dpi resolution option is set for the file selected bythe user, the print driver of the print control terminal 10 may generateraw data with 1200×1200×8 bit resolution. The generated print data istransferred to the image forming apparatus 100. In the example explainedabove with reference to FIG. 2, the print data is transferred from theprint control terminal 10 to the image forming apparatus 100 via theprint driver. However, this was written only for illustrate purpose, andaccordingly, other examples are also possible. For example, the fileitself may be directly transferred to the image forming apparatus 100 bya direct-print method.

When the print data is received, the image forming apparatus 100 maygenerate a bitmap image of 1200×1200×8 bit by carrying out rendering ofthe received print data. At operation 230, the image forming apparatus100 may then convert the bitmap image (1200×1200×8 bit) into binary databy carrying out halftoning. Herein, the conventional way of halftoningwhich is generally used in color laser printers or black and white laserprinters may be implemented.

In one embodiment, the generated binary data 1200×1200×1 bit is shown atlocations 311, 321, 331, 341 of FIG. 3, in which ‘1 ₍₂₎’ is where a dotis marked, ‘0 ₍₂₎’ is where a dot is not marked. Referring to FIG. 3,the binary data generated as a result of halftoning have 1200 dpi pitchin both main-scan and sub-scan directions.

Next, at operation 240, multi-bit data (1200×600×2 bit) may be generatedby combining two successive bits in sub-scan direction of the generatedbinary data (1200×1200×1 bit). The “sub-scan direction ” herein refersto the direction of print paper, and the “main-scan direction” refers tothe operation direction of LSU which is perpendicular to the directionof the print paper.

In one embodiment, the examples of the generated multi-bit data(1200×600×2 bit) are shown at locations 312, 322, 332, 342 of FIG. 3.Referring to FIG. 3, as a result of data combination, each block has2-bit data of ‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’. Each of themulti-bit data has 1200 dpi pitch in the main-scan direction and has 600dpi pitch in the sub-scan direction. Comparing the binary data with themulti-bit data reveals that change occurs only in the form of the data,but not in the data amount.

Next, at operation 250, the generated multi-bit data is transferred tothe print engine, and the print engine generates dots according to thetransferred multi-bit data. To be specific, the print engine unit mayform white dots with respect to the transferred multi-bit data ‘00 ₍₂₎’,full-size dots with respect to ‘11 ₍₂₎’, and same half-size dots withrespect to ‘01 ₍₂₎’ and ‘10 ₍₂₎’.

In one embodiment, the examples of the generated dots are shown atlocations 313, 323, 333, 343 of FIG. 3. Referring to FIG. 3, white dotsare formed with respect to ‘00 ₍₂₎’ of the multi-bit data, half-sizedots are formed with respect to ‘01 ₍₂₎’, ‘10 ₍₂₎’, and full-size dotsare formed with respect to ‘11 ₍₂₎’. The “half-size dot” herein refersto a dot formed by an electronic/electric signal smaller than afull-size dot signal.

At operation 260, toner may be attached to the formed dots to thus forman image on the print paper. Since the generated dot signal is not adigital signal but an analog signal at the print engine, the signal hasthe sinusoidal form as illustrated in FIGS. 4 to 8. Due to such physicalphenomenon, the toner images coagulate as illustrated at locations 314,324, 334, 344 of FIG. 3. That is, according to the property of a lasersignal, the normalization curves overlap with each other, and as aresult, physical output characteristic of toner coagulation appearsbetween adjacent locations when the toner is attached onto the paper.

Considering the above characteristic, data is processed to haveresolution of 600 dpi in the sub-scan direction (i.e., the print paperis moved at 600 dpi pitch (40 μm)), but the output has the lines of 1200dpi line pitch on the print paper due to multi-bit print signal and alsothe above-mentioned physical characteristics.

FIG. 4 is a view illustrating the characteristics of a laser signal inthe main-scan direction.

Referring to FIG. 4, dots are formed at 1200 dpi pitch in the main-scandirection, with each dot being in sinusoidal form. Although theillustrated example shows each dot as full-size dots, white dot orhalf-size dot may also be formed.

FIGS. 5 to 8 illustrate the characteristics of a laser signal in thesub-scan direction.

Referring first to FIGS. 5 and 6, dots are formed at 600 dpi pitch inthe sub-scan direction. To be specific, FIG. 5 illustrates full-sizedots 510, and FIG. 6 illustrates half-size dots 610. Comparing FIGS. 5and 6 reveals that the half-size dot has a relatively smaller electricsignal than full-size dot.

Referring to FIGS. 7 and 8, there are half-size dots 710, 810 andfull-size dots 720, 820 successively in the sub-scan direction. If thehalf-size dots 710, 810 and the full-size dots 720, 820 are formedsuccessively as explained above, due to higher electric signal of thefull-size dots 720, 810, toner intended for the half-size dots 710, 810is attracted toward the full-size dots 720, 820 and as a result,attached to locations 710′, 810′ between the half-size dots 710, 810 andthe full-size dots 720, 820. However, the toner lines 710′, 810′ alsohave 1200 dpi pitch in the sub-scan direction.

FIG. 9 illustrates an image forming method according to an exemplaryembodiment.

Referring to FIG. 9, first, at operation 910, print data is received. Tobe specific, the print data or vector print data with the resolution of1200×1200 dpi may be received from the print control terminal 10.

At operation 920, the received print data is converted into a bitmapimage by rendering. To be specific, the print control terminal 10 maygenerate a bitmap image by carrying out rendering of the received printdata. Herein, the rendering may convert not only raw data at resolutionof 1200×1200 dpi into a bitmap image with 1200×1200 dpi resolution, butalso convert raw data or vector data at resolution lower than 1200×1200dpi into bitmap image at 1200×1200 dpi resolution. The generated bitmapimage may be stored temporarily.

At operation 930, halftoning is carried out with respect to the bitmapimage so that binary data is generated. To be specific, the halftoningsuch as screening or dithering may be carried out with respect to thebitmap image rendered at the previous step, to thus generate binarydata.

At operation 940, a plurality of successive binary data of the generatedbinary data is combined to generate multi-bit data. To be specific, atleast one 2-bit data may be generated from among ‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10₍₂₎’ and ‘11 ₍₂₎’ by combining two successive binary data in theadvancing direction (i.e., sub-scan direction) of the print paper. Byway of example, if data ‘0 ₍₂₎’, ‘0 ₍₂₎’, ‘0 ₍₂₎’, ‘1 ₍₂₎’ successivelyexist in the sub-scan direction, two 2-bit data of ‘00 ₍₂₎’, ‘01 ₍₂₎’may be generated. The generated data may be stored temporarily. To bespecific, the multi-bit data may be stored in a manner of writing overthe binary data which is generated in the previous step.

At operation 950, an image may be formed using the generated multi-bitdata. To be specific, using a print engine with the resolution of 1200dpi in main-scan direction and 600 dpi in sub-scan direction, a whitedot may be formed if the multi-bit data is ‘00 ₍₂₎’, a half-size dot isformed if the multi-bit data is ‘01 ₍₂₎’ and ‘10 ₍₂₎’, and a full-sizedot is formed if the multi-bit data is ‘11 ₍₂₎’. The half-size dot mayhave 1200 dpi pitch. An image may then be formed as toner is attached tothe plurality of dots as formed, and then transferred onto a printpaper.

As explained above, the image forming method according to an exemplaryembodiment converts only the form of the binary data at 1200×1200 dpiresolution into multi-bit data form, without affecting the binary dataitself, and transfers the converted data to the print engine. Then asthe print engine forms half-size dots at 1200 dpi pitch with respect to‘01 ₍₂₎’ and ‘10 ₍₂₎’ of the transferred multi-bit data, print job iscarried out at the resolution of 1200×1200 dpi as desired by the user.The image forming method of FIG. 9 may be implemented in an imageforming apparatus as the one with the construction explained above withreference to FIG. 1, or image forming apparatuses with otherconstructions. It is also understood that a resolution of 1200×1200 dpiis only an example, but can be also higher resolution than 1200×1200dpi.

The foregoing exemplary embodiments and advantages are merely exemplaryand are not to be construed as limiting the embodiments. The presentteaching can be readily applied to other types of apparatuses. Also, thedescription of the exemplary embodiments is intended to be illustrative,and not to limit the scope of the claims, and many alternatives,modifications, and variations will be apparent to those skilled in theart.

What is claimed is:
 1. An apparatus comprising: a communication interface unit which receives print data; a rendering unit which converts the received print data into a bitmap image by rendering; a binarization unit which generates binary data by carrying out halftoning with respect to the bitmap image; a data combining unit which generates multi-bit data by combining a plurality of successive binary data of the generated binary data; and a print engine which forms an image using the generated multi-bit data.
 2. The apparatus of claim 1, wherein the received print data comprise raw data with 1200×1200 dpi (dots per inch) resolution.
 3. The apparatus of claim 1, wherein the rendering unit generates bitmap data at 1200×1200 dpi resolution from the received print data.
 4. The apparatus of claim 1, wherein the print engine unit has 1200 dpi resolution in a main-scan direction and 600 dpi resolution in a sub-scan direction.
 5. The apparatus of claim 1, wherein the data combining unit combines a plurality of successive binary data in a sub-scan direction of a print paper.
 6. The apparatus of claim 1, wherein the data combining unit generates at least one 2-bit data from among ‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’, by combining two binary data in a vertical direction from among the binary data.
 7. The apparatus of claim 1, wherein the print engine unit forms at least one of: white dot, half-size dot, and full-size dot.
 8. The apparatus of claim 7, wherein the print engine unit forms the half-size dot with respect to ‘01 ₍₂₎’ and ‘10 ₍₂₎’ of the 2-bit data.
 9. The apparatus of claim 7, wherein the dot formed by the half-size dot has 1200 dpi pitch.
 10. The apparatus of claim 1, further comprising: a storage unit to store the print data.
 11. An image forming method comprising: receiving print data; rendering to convert the received print data into a bitmap image; halftoning with respect to the bitmap image to generate binary data; data combining to generate multi-bit data by combining a plurality of successive binary data of the generated binary data; and forming an image using the generated multi-bit data.
 12. The image forming method of claim 11, wherein the received print data comprise raw data with 1200×1200 dpi (dots per inch) resolution.
 13. The image forming method of claim 11, wherein the rendering comprises generating bitmap data at 1200×1200 dpi resolution from the received print data.
 14. The image forming method of claim 11, wherein the forming an image comprises using a print engine having 1200 dpi resolution in a main-scan direction and 600 dpi resolution in a sub-scan direction.
 15. The image forming method of claim 11, wherein the data combining comprises combining a plurality of successive binary data in an advancing direction of a print paper.
 16. The image forming method of claim 11, wherein the data combining comprises generating at least one 2-bit data from among ‘00 ₍₂₎’, ‘01 ₍₂₎’, ‘10 ₍₂₎’ and ‘11 ₍₂₎’, by combining two binary data in a vertical direction from among the binary data.
 17. The image forming method of claim 16, wherein the forming an image comprise forming at least one of: white dot, half-size dot, and full-size dot.
 18. The image forming method of claim 17, wherein the forming an image comprises forming the half-size dot with respect to ‘01 ₍₂₎’ and ‘10 ₍₂₎’ of the 2-bit data.
 19. The image forming method of claim 17, wherein the dot formed by the half-size dot has 1200 dpi pitch.
 20. An image forming method, comprising: receiving printing data having m×n dpi; converting the received printing data into reduced size dot in a sub-scanning direction resolution to print out m×n dpi resolution; and printing the converted printing data out with m×n dpi resolution using a m×½ n dpi print engine unit, wherein the m is main-scanning direction resolution and the n is sub-scanning direction resolution.
 21. The image forming method of claim 20, wherein m=n and m=1200. 